1. Field of the Invention
This invention relates to a connector for connection to a gas generator (often called xe2x80x9csquibxe2x80x9d).
2. Summary of the Prior Art
In automotive applications such as airbag and seat belt pretentioners, explosive devices are provided, such devices often called squibs. Squibs are typically provided with a pair of contacts projecting within a cavity for receiving and mating with a complementary connector, commonly called squib connector. A squib connector assembly typically comprises a short circuit element that bridges the pin contacts of the squib in the uncoupled state. During plugging, the shorting contacts are biased by the squib connector to break the short circuit. The short circuit contact is often provided within a housing fastened to the squib housing.
Conventional squib connectors have resilient latches that engage shoulders of the squib housing, the latches shaped as cantilever beams attached to the connector housing at one end, and extending to a free end. In some designs as disclosed in U.S. Pat. No. 5,275,575, and EP 736934, the squib connector latches are in form of resilient cantilever beams that automatically latch to shoulders of the squib housing, wherein a further safety peg is inserted between the latch and connector housing for preventing inadvertent release of the connector. The connector is released by removing the safety insertion element and pulling upwardly on the connector, whereby conical or tapered latching surfaces on the resilient latch arms assist inward biasing of the latches for disengagement. As the latches provide a certain resistance, extraction requires relatively high forces that may damage the latches or the connector, especially after a few plugging and unplugging cycles. In view of reducing insertion forces during plugging it is known to positively outwardly bias the latch members during plugging with the safety element, as disclosed in U.S. Pat. No. 5,525,512. Unplugging may however be unreliable, if the resiliency of the latches diminishes over the life of the connector such that the latches do not fully inwardly bias to the rest position during uncoupling. One of the problems with all of the above described designs, is that the need to insert a safety element between the locking or latch arm and the connector housing reduces available space for the housing and latches. The latches are thus relatively flimsy, or the housing portion receiving the terminals needs to be made more compact. It would be desirable to improve the robustness and/or provide more space for the connector housing. It may be noted that the squibs have cavities with standardised dimensions, typically in order of approximately 8-10 mm diameter.
Another problem of resilient latches is the resistance to uncoupling once the safety peg is removed, which is sometimes quite high when the connector is new, but that reduces after use due to wear and reduced elasticity of the plastic housing material subject to heat and vibration. It would be desirable to avoid high resistance and varying plugging/unplugging characteristics.
In many squib connectors, it is also common to provide latching arms that resiliently latch during coupling, but that require special tooling for uncoupling, for example as shown in U.S. Pat. No. 5,609,498. The use of special tooling is however often undesirable as it increases the costs of service and maintenance.
It is an object of this invention to provide a squib connector that can be rapidly and easily plugged and unplugged from a squib, but which is nevertheless particularly safe, reliable and robust. In particular, reliability of the connection should be maintained over the life of the connector, unaffected by the number of plugging and unplugging operations or environmental conditions such as heat and vibration.
Objects of this invention have been achieved by providing a squib connector according to claim 1. Disclosed herein is a squib connector having a mating portion adapted to be received within a cavity of a squib for electrical connection thereto, the mating portion of the squib connector comprising a housing and a locking element mounted on the housing, the locking element comprising a locking portion engagable against a complementary shoulder of the squib for securing the connector in the squib, wherein the locking element is movably mounted on the housing and further comprises a camming portion adapted to cam against a complementary camming portion of the housing thereby biasing the locking portion into engagement with the squib complementary latching shoulders when the locking element is moved from an unlocked position to a locked position during coupling of the connector to the squib. Advantageously therefore, locking can be quickly and easily effected whilst ensuring a secure fully locked position, and without depending on resiliency of the latches. High temperature, vibration, or other factors that may affect the strength and resiliency of the connector housing material will therefore not affect the reliability and ease of plugging and unplugging of the squib connector. Furthermore a robust construction may be provided by avoiding insertion of a safety element.
The locking portion may be provided on cantilever beams attached at one end remote from a mating end of the connector mating portion to the locking element, and extending therefrom to a free end directed towards the connector mating face. In their natural or free standing position the locking portions may be provided in a substantially fully disengaged position, the latches being fully outwardly biased into engagement with the squib latching shoulders during mating. The latter enables a relatively low plugging, and unplugging force to be provided. The locking element may be provided slideable in the mating direction, against an outer surface of the mating portion. The housing camming portion may comprise an outwardly protruding tapered surface proximate the mating face, for engaging the locking element camming portions provided proximate free ends of locking arms. The locking portion may be provided with a second release camming surface that engages the squib during uncoupling for biasing the locking portions out of the locked position. The release camming surface may be tapered and may form part of a locking surface of the locking portion that engages the complementary squib locking shoulder. A particularly simple and robust latching is thus provided. The connector housing may further comprise a lock return element that engages the locking arms or portions in their unlocked position to ensure the locking arms are returned fully to their initial position prior to coupling. The lock return elements also help to protect the locking arms from damage. The locking element may further comprise latches that secure the locking element in the fully coupled position relative to the connector housing, whereby the latches have camming portions that push the housing in the plugging direction during unlatching. This ensures that the locking element is returned to the uncoupled position during unplugging of the connector and squib.
Further advantageous aspects of this invention will be described in the claims, or will be apparent from the following description and drawings.